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Advice and suggestions needed for cement "bridge"


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JohnSurrey
2 hours ago, Jawny said:

That’s the way I’ve done this many times for countertops and such.  Pinoy construction techniques. What I don’t know is the amount of rebar to use, cement mix and that sort of stuff.  My concern is the ability of the slab to support the weight of a car. 

https://www.youtube.com/watch?v=o3raQVXb4jM   ?

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Couldn't you get something similar to a metal grate they use for covering drainage canals with.

Use a cement drainage pipe., then cover it with cement. It's what we did, supported a cement truck.

If it was me I`d weld 16mm rebar into the exact size grid and tie flat GI sheet underneath that grid..Put the grid in place and concrete over.

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The YouTube instruction video was impressive, but way beyond me. Too much engineering jargon and such.  

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fred42

If it was me I`d weld 16mm rebar into the exact size grid and tie flat GI sheet underneath that grid..Put the grid in place and concrete over.

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Dafey

Hey Jawny,

We are in Western Leyte and they are doing the same widening in our area. Most of the drainage ditches they are building have a concrete slab on top but I can see them saving money at a residence and telling the owner to do as he wishes.

The rebar ramp/bridge is plenty strong enough and leaves the option to remove it for cleaning from time to time. It's also the easiest. The question is...are the walls of the drainage ditch strong enough to hold the weight of a car? You might ask the construction crew. Also, you can look at the work they have finished up the road. That will give you some more ideas.

If you pour cement, I've seen them use a corrugated roof panel, (Steel so you can spot weld rebar to it), for the base and no cement will permeate. You can also make it a curved bridge by arcing it then welding your rebar to hold it in place while you pour.

I haven't seen anyone answer the technical problems as to how thick, how many rebars, etc. but I think @oztony has some experience with pouring concrete.

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The use of the preformed cement slabs is being used in many of the sections along the highway.  However, this is something that is done later,,and by some sort of subcontracting.  In effect, no assurances when the slabs will be made and put in place. 

My garage is slightly elevated in relation to the highway, so if slabs were used, I’d have to create some sort of slope to get up to the level of the garage floor.  In effect, I have to do s9me cement work whatever the DPWH does.

As well, no assurances the slabs will support the weight of the car.  I certainly don’t want to be the first to test the slab.  I’ve seen many homes with cement driveways as I am describing.  I am certain the walls of the canal are no intended to support much weight.  My intention is to extend the bridge/ramp so the support is from the garage floor and highway base. 

By dojng the work myself, I can get it done sooner and with confidence the materials and labor is done correctly.

As far as cleaning under the drive, small workers can take care of that.  

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I have tried to insert a photo (jpg and pdf) but won’t work except as an attachment  

The best way I can describe the canal is a 50cm wide canal built into a long hole dug alongside the highway, about 1.6 meters wide.

The bridge I will build will need to span the 50cm canal.

I am going to use a plywood base, supported by coco wood.  I’ll probably use 12mm rebar spaced as 20 cm squares, tie wired together.  I’ll use a standard cement mix, and let it cure for a week, maybe two.  

Pill leave the coco wood supports in place for a long while.  jawny.thumb.png.ba18da83c6a5c86ff19cd0b12eb670bc.png

IMG_7089.pdf

Edited by Jawny
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SkyMan
7 hours ago, Jawny said:

My intention is to extend the bridge/ramp so the support is from the garage floor and highway base. 

You're not talking about pouring your bridge onto the hiway, right?  Just up to the edge?  I would imagine there is some rule against encroaching on the hiway and they might make you redo it or come by and smash off the edge.  Anyway, make sure you tamp down the soil between the hiway and the canal good.  Also, it looks like their digging has eroded under your drive and it probably won't be possible to pack sufficient material back under.  You may want to smash some of your existing concrete back a bit to add some fill and tamp.

For short term like now til the canal is done you can get some 2X10 (6'? 8'?) coco planks.

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What is not shown in the image is my parked car, in the garage. Any floor reinforcement will have to be done later.  

The DPWH contractor will build a stone cement wall where the backhoe has removed fill.  As well, empty space will be filled. In effect, they have dug a channel into which a cement canal will be placed.  If there were no garage, they would be reinforcing the sides so the canal will remain in place.

i won’t have to place anything on the highway.  

If you look further into the distance, you can see a house which is extremely close to the location where the canal will go.  In fact, their balcony extends just over the highway right of way.  Not to worry, the electrical utility pole is also in the highway right of way.  

I have a house with a sari sari store in a close by barangay.  We have already made preps for when the widening comes.  About half of the store floor space will be gone.

Im not complaining.  I’ve seen several two story houses reduced to rubble in the process.  Good news for our gardeners as we get lots of free plants as the work progresses.

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Just buy the DPWH workers a few snacks and they will fix your drive way entrance for you at least they did on our road not just for us but for everyone that needed access across the drainage ditch

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43 minutes ago, cogon88 said:

Just buy the DPWH workers a few snacks and they will fix your drive way entrance for you at least they did on our road not just for us but for everyone that needed access across the drainage ditch

Good idea, and it does work.  We’ve already done this on several occasions.  The crews change frequently, so the favors need to be renewed.  We’ve had them move equipment and even pour a short bit of driveway.

The problem is the current crews are limited with resources and such.  They can only use what they are able to have access to. 

My intentions are to have the materials and plan ready when they finally have the canal in place.  If the crews are able to do something that will work, we'll just let them.  

I was just hoping for technical suggestions as to construct the flooring.  I’ve done flooring many times, but never over a gap like the canal will make.

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SkyMan
19 hours ago, Jawny said:

What is not shown in the image is my parked car, in the garage. Any floor reinforcement will have to be done later.  

I was only thinking take off 6-8 inches which you could do with the car there.  Or you could remove the car via coco planks.

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I have a relative who has compressed helium.  I am planning to change the heavy air in the tires with helium so there is less weight on the garage floor.  

 

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to_dave007

If it were me I'd overdo it a bit on the rebar..  mainly because I hate seeing those slabs over canal that are busted and you need to watch where your wheel goes.

Also..  what's heaviest vehicle that will EVER drive over the slab.  Multicab full of sand?  your car full of LINC members?  The Hummer you buy when you win the lottery?  or what?

Cost difference to overdo it a bit isn't much.

 

Edited by to_dave007
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Davaoeno
23 minutes ago, to_dave007 said:

If it were me I'd overdo it a bit on the rebar..  mainly because I hate seeing those slabs over canal that are busted and you need to watch where your wheel goes.

Also..  what's heaviest vehicle that will EVER drive over the slab.  Multicab full of sand?  your car full of LINC members?  The Hummer you buy when you win the lottery?  or what?

Cost difference to overdo it a bit isn't much.

 

I agree- rebar is cheap.

Edited by Davaoeno
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